docs: fixed spelling mistake (#104)

* docs: fixed spelling mistake

* docs: fix another small text error

Author: jasoniangreen

demo/src/Home.js

@@ -10,7 +10,7 @@ export default () => (
         <a href={'https://bvaughn.github.io/react-virtualized/#/components/List'}>react-virtualized</a>.
       </p>
       <p>Its main goal is to display tree like data in a beautiful and fast way.</p>
-      <p>Being a reactive library it uses children functions to achieve maximum extansability</p>
+      <p>Being a reactive library it uses children functions to achieve maximum extensibility</p>
       <p>
         The core idea behind it is that anyone using it is enable to create a tree as they wich just by rendering their
         own components or components exported by the tree

demo/src/docs/filtering.md

@@ -1,5 +1,5 @@
 # FilteringContainer
-FilteringComponent is a component that can be used to wrap to Tree in order to get filtering and group functionality for free.
+FilteringComponent is a component that can be used to wrap the Tree in order to get filtering and group functionality for free.
 
 To use this component you should know a little bit about [using functions as children](https://codedaily.io/tutorials/6/Using-Functions-as-Children-and-Render-Props-in-React-Components).